During the study, daily asthma symptoms, peak expiratory flow, rescue and background medication use, and compliance with the study medication will be recorded via subject diary. Treatment-Emergent Adverse Events (TEAEs) will be assessed and recorded throughout the study. At screening and subsequent visits, patients will undergo physical and vital signs examinations, spirometry measurements, and 12-lead ECG. Routine hematology, blood chemistry, and pregnancy testing will be performed before enrollment and at end of study. 24-hr urine cortisol and creatinine will be assessed before and after the first dose and just before the last dose of study treatment.